I am looking for a Korean equivalent of the expression in this sentence:
"He'll skin me alive if he finds out I'm playing games in the class"
or
"I'll get skinned if he finds out I'm playing games in class"
Is there an equivalent Korean expression that can be used humorously?
You can use the negative form of the verb 가만두다 which means:
동사 (verb)
「(object)…을」 건드리거나 상관하지 않고 그대로 두다. (literally) Subject doesn't touch nor care and leave the object be. (to tolerate)
다시 나쁜 짓 하는 날엔 너를 가만두지 않겠다. (literally) I will never forgive / tolerate you when you do something bad again.
Your example sentence
He'll skin me alive if he finds out I'm playing games in the class.
could be translated to:
내가 수업 중에 게임을 하는 것을 그가 알게 되면 (그는) 나를 (날) 가만두지 않을 거야.
Of course, the literal translation of 'to skin someone alive' is '산 채로 가죽을 벗기다', but it will sound too cruel and harsh if you translate it to
내가 수업 중에 게임을 하는 것을 그가 알게 되면 (그는) 나를 (날) 산 채로 가죽을 벗길 거야.
It makes sense, but is neither idiomatic nor natural.
You could use '산 채로 가죽을 벗기다' when you are full of anger and revengeful thoughts.
I'll get skinned alive if the teacher catches me playing games in class is an imagery that English speakers say idiomatically but don't really envision the true imagery of when speaking.
The idiomatic phrase that would feel the same would be to simply say Get caught playing games in class, and (he'll) kill you!
교실에서 게임하다 걸리면 넌 죽을 거다!
1) 그가 나를 사진 찍었다. He took my photo
나는 낙인 찍혔다. I received totally bad reputation
누구 찍었니 ? Who do you vote ?
도끼로 나무를 찍다. I chop a tree with an ax.
2) I think that 찍혔어 is suitable for "He'll skin me alive if he finds out I'm playing games in the class"
Here "my impression is printed in his eyes" is a more correct meaning.
A : 나 선생님한테 완전 찍혔어 I was totally pictured by the teacher.
B : 왜 ? Why ?
A : 수업시간에 잤어. 나를 노려 봤어 He saw me take a nap in his class and gave me a fierce look.
B : 조심해. Be careful next time.
